High power radio-frequency switching topology and method

ABSTRACT

Aspects and examples described herein provide a radio-frequency switching circuit, switching device, and related methods. In one example, a radio-frequency switching device includes an input path configured to receive a radio-frequency signal, a plurality of output paths each configured to provide the radio-frequency signal, and a plurality of radio-frequency sub-networks each coupled to the input path and configured to direct the radio-frequency signal, each of the plurality of sub-networks including at least a first radio-frequency circuit having a first series of directly biased transistors, a second radio-frequency circuit having a second series of directly biased transistors, and a direct current blocking network interposed between the first radio-frequency circuit and the second radio-frequency circuit, each output path of the plurality corresponding to at least one of the plurality of radio-frequency sub-networks.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 120 of co-pendingU.S. application Ser. No. 15/834,573, titled “HIGH POWER RADIO-FREQUENCYSWITCHING TOPOLOGY AND METHOD,” filed on Dec. 7, 2017, which claims thebenefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No.62/431,655, titled “HIGH POWER RADIO-FREQUENCY SWITCHING TOPOLOGY ANDMETHOD,” filed on Dec. 8, 2016, each of which is herein incorporated byreference in its entirety for all purposes.

BACKGROUND

Many communication terminal designs, such as those for smart-phones andtablets, require operation over numerous communication bands. Forexample, a typical radio-frequency base-station may connect one or moremobile devices to each other, or to a wider wireless network. Thesemulti-band devices generally use one or more transmit/receive circuitsto generate and amplify signals for transmission, or amplify signalsonce received. Often, these multi-band devices will include a singleantenna to transmit and receive signals over the specified communicationbands. However, more recently, multi-band devices may use multipleantennas, each communicating over various communication bands.Accordingly, typical multi-band devices require a switching element todirect the signal through the proper transmit or receive path. Highpower switching applications for radio frequency signals are typicallyaddressed using one or more PIN diodes.

SUMMARY

Aspects and examples relate to electronic systems and, in particular, toradio-frequency transistor-based switching circuits. Various aspects andexamples replace PIN diodes within a switching circuit with field effecttransistors to enable high power radio-frequency switching based on acomparatively low direct current bias current or voltage. Particularaspects and examples may include one or more direct current biasnetworks, and one or more direct current blocking networks, for directlybiasing each field effect transistor within the switching circuit. Suchan arrangement allows the circuit to scale accordingly underincreasingly large radio-frequency signal power. Moreover, the one ormore direct current bias networks within the switching circuits ofvarious examples individually bias each field effect transistor toensure proper operation of each field effect transistor regardless ofthe radio-frequency signal power handling requirements of the circuit.

According to at least one aspect, provided is a radio-frequency circuit.In one example, the radio-frequency circuit comprises a series oftransistors including at least a first transistor and a secondtransistor and each having at least a source, a gate, and a drain, and aplurality of direct current bias networks including a first directcurrent bias network coupled to the gate of the first transistor, asecond direct current bias network coupled to the gate of the secondtransistor, and a third direct current bias network coupled to the drainof the first transistor and the source of the second transistor, each ofthe plurality of direct current bias networks being configured todirectly bias the corresponding transistor to direct a radio-frequencysignal through the series of transistors.

In one example, the radio-frequency circuit further comprises a firstvoltage distribution network coupled to the source of the firsttransistor and the third direct current bias network. In a furtherexample, the radio-frequency circuit further comprises a second voltagedistribution network coupled to the drain of the second transistor andthe third direct current bias network. According to an example, thefirst transistor is a first field effect transistor and the secondtransistor is a second field effect transistor. In one example, theradio-frequency circuit further comprises a gate bias source coupled tothe first direct current bias network and the second direct current biasnetwork. According to one example, radio-frequency circuit furthercomprises a source/drain bias source coupled to the third direct currentbias network.

According to certain examples, the radio-frequency circuit furthercomprises an input path configured to receive the radio-frequencysignal, and an output path configured to provide the radio-frequencysignal. In one example, the input path is configured to receive theradio-frequency signal in series or in shunt with the series oftransistors. In a further example, the input path is configured toreceive the radio-frequency signal from a transmission line of aradio-frequency power amplifier.

According to at least one example, the radio-frequency circuit furthercomprises a first direct current blocking network coupled to the outputpath of the radio-frequency circuit. In a further example, theradio-frequency circuit further comprises a second direct currentblocking network coupled to the input path of the radio-frequencycircuit.

In one example, at least one of the plurality of direct current biasnetworks is a ¼ wavelength transformer. According to another example, atleast one of the plurality of direct current bias networks is aninductor circuit. In certain examples, the series of transistor areintegrated within a shared die, and in some examples, the plurality ofdirect current bias networks is integrated within the shared die.

According to certain aspects, provided is a radio-frequency switchingdevice. In one example, the radio-frequency switching device comprisesan input path configured to receive a radio-frequency signal, aplurality of radio-frequency sub-networks each coupled to the input pathand configured to direct the radio-frequency signal, each of theplurality of sub-networks including at least a first radio-frequencycircuit having a first series of directly biased transistors, a secondradio-frequency circuit having a second series of directly biasedtransistors, and a direct current blocking network interposed betweenthe first radio-frequency circuit and the second radio-frequencycircuit, and a plurality of output paths each configured to provide theradio-frequency signal, each output path of the plurality correspondingto at least one of the plurality of radio-frequency sub-networks.

According to certain examples, the radio-frequency switching devicefurther comprises a plurality of transmission lines, at least one of theplurality of transmission lines being interposed between the input pathand a corresponding one of the plurality of radio-frequencysub-networks. In a further example, each of the plurality oftransmission lines is a ¼ wavelength transformer. According to oneexample, the first radio-frequency circuit further includes a firstplurality of direct current bias networks configured to directly biasthe first series of transistors, and the second radio-frequency circuitfurther includes a second plurality of direct current bias networksconfigured to directly bias the second series of transistors.

According to an example, the first radio-frequency circuit furtherincludes a first voltage distribution network coupled to at least one ofthe first plurality of direct current bias networks, and the secondradio-frequency circuit further includes a second voltage distributionnetwork coupled to at least one of the second plurality of directcurrent bias networks. In one example, the first series of transistorsincludes a first transistor and a second transistor, and the secondseries of transistors includes a third transistor and a fourthtransistor. According to an example, each of the first transistor, thesecond transistor, the third transistor, and the fourth transistor is afield effect transistor.

In one example, the plurality of radio-frequency sub-networks includes afirst radio-frequency sub-network and a second radio-frequencysub-network, and the plurality of transmission lines includes a firsttransmission line and a second transmission line, the first transmissionline being interposed between the first radio-frequency sub-network andthe input path, and the second transmission line being interposedbetween the second radio-frequency sub-network and the input path.According to one example, the plurality of radio-frequency sub-networksfurther includes a third radio-frequency sub-network and a fourthradio-frequency sub-network, and the plurality of transmission linesfurther includes a third transmission line and a fourth transmissionline, the third transmission line being interposed between the thirdradio-frequency sub-network and the input path, and the fourthtransmission line being interposed between the fourth radio-frequencysub-network and the input path.

According to certain examples, at least one of the plurality ofradio-frequency sub-networks is configured receive the radio-frequencysignal in series or in shunt with the corresponding first series oftransistors. In one example, the input path is configured to receive theradio-frequency signal from an output stage of a radio-frequency poweramplifier.

According to certain aspects, provided is a method for providing aradio-frequency signal. According to one example, the method comprisesreceiving a radio-frequency signal at an input path, receiving a firstdirect current bias from a first direct current bias network at a gateof a first transistor, receiving a second direct current bias from asecond direct current bias network at a gate of a second transistor,receiving a third direct current bias from a third direct current biasnetwork at a drain of the first transistor and a source of the secondtransistor, directing the radio-frequency signal from the input paththrough the first transistor and the second transistor, and providingthe radio-frequency signal at an output path.

In one example, the method further comprises distributing the thirddirect current bias to the source of the first transistor with a firstvoltage distribution network coupled to the direct current bias network.According to an example, the method further comprises distributing thethird direct current bias to the drain of the second transistor with asecond voltage distribution network coupled to the direct current biasnetwork. In one example, the method further comprises blocking at leastone of the first direct current bias and the second direct current biaswith a direct current blocking network coupled to the output path.According to certain examples, receiving the radio-frequency signal atthe input path includes receiving the radio-frequency signal in seriesor in shunt with the first transistor.

According to another aspect, provided is a communication terminal. Inone example, the communication terminal comprises a transceiverconfigured to generate a radio-frequency signal, a radio-frequencymodule coupled to the transceiver and including at least oneradio-frequency circuit, the radio-frequency circuit including a seriesof transistors and a plurality of direct current bias networksconfigured to directly bias the series of transistors to direct theradio-frequency signal, and an antenna in communication with theradio-frequency module, the antenna configured to transmit theradio-frequency signal.

In one example, the radio-frequency circuit includes the radio-frequencycircuit as shown and described herein. In certain examples, thecommunication terminal further comprises a transmission line interposedbetween the transceiver and the radio-frequency module. In a furtherexample, the transmission line includes a ¼ wavelength transformer. Inone example, the communication terminal further comprises a poweramplifier coupled to the radio-frequency circuit and configured toprovide an amplified radio-frequency signal.

According to another aspect, provided is a radio-frequency circuit. Inone example, the radio-frequency circuit comprises a gate bias source, asource/drain bias source, a plurality of switching circuits each coupledin parallel between the gate bias source and the source/drain biassource, and each including a corresponding transistor coupled in serieswith the corresponding transistor of each other switching circuit, and adirect current bias network interposed between the source/drain biassource and each switching circuit of the plurality of switchingcircuits.

In certain examples, each switching circuit of the plurality ofswitching circuits further includes an additional direct current biasnetwork coupled between the gate bias source and the correspondingtransistor. In one example, each switching circuit of the plurality ofswitching circuits further includes a voltage distribution networkcoupled to the corresponding transistor. According to at least oneexample, the corresponding transistor of each switching circuit is afield effect transistor having at least a gate, a source, and a drain.

According to one example, the plurality of switching circuits includes afirst switching circuit and a second switching circuit, the additionaldirect current bias network of the first switching circuit and thesecond switching circuit being coupled to the gate of the correspondingfield effect transistor. In one example, the voltage distributionnetwork of the first switching circuit is coupled to the source of thecorresponding field effect transistor, and the voltage distributionnetwork of the second switching circuit is coupled to the drain of thecorresponding field effect transistor. According to one example, thedirect current bias network is coupled to the drain of the correspondingfield effect transistor of the first switching circuit, and the sourceof the corresponding field effect transistor of the second switchingcircuit. In one example, the radio-frequency circuit further comprises adirect current blocking network coupled to at least one of the pluralityof switching circuits.

Still other aspects, examples, and advantages of these exemplary aspectsand implementations are discussed in detail below. Examples disclosedherein may be combined with other examples in any manner consistent withat least one of the principles disclosed herein, and references to “anexample,” “some example,” “an alternate example,” “various examples,”“one example” or the like are not necessarily mutually exclusive and areintended to indicate that a particular feature, structure, orcharacteristic described may be included in at least one example. Theappearances of such terms herein are not necessarily all referring tothe same example.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one example are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide illustration and afurther understanding of the various aspects and examples, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of the disclosure. In thefigures, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in every figure.In the figures:

FIG. 1A is a block diagram of one example of a radio-frequency circuitaccording to aspects disclosed herein;

FIG. 1B is a more comprehensive block diagram of the radio-frequencycircuit of FIG. 1A, according to aspects disclosed herein;

FIG. 1C is a simplified block diagram of the radio-frequency circuit ofFIG. 1B, according to aspects disclosed herein;

FIG. 2 is a block diagram of one example of a switching device accordingto aspects disclosed herein;

FIG. 3 is a block diagram of one example of a radio-frequencysub-network which may be included within the example switching device ofFIG. 2, according to aspects disclosed herein;

FIG. 4 is a block diagram of one example of a radio-frequency moduleaccording to aspects disclosed herein;

FIG. 5 is a block diagram of one example of a communication terminal inwhich implementations of the radio-frequency module of FIG. 4 may beused, according to aspects disclosed herein; and

FIG. 6 is a process flow illustrating one example of a process forproviding a radio-frequency signal according to aspects disclosedherein.

DETAILED DESCRIPTION

Aspects and examples relate to electronic systems and, in particular, toradio-frequency transistor-based switching circuits. Various aspects andexamples replace PIN diodes with field effect transistors to enable highpower radio-frequency switching based on a comparatively low directcurrent bias current or voltage. Particular aspects and examples mayinclude one or more direct current bias networks individually coupled toa corresponding field effect transistor. Specifically, each directcurrent bias network may be configured to directly bias thecorresponding field effect transistor. Certain aspects and examples mayfurther include one or more direct current blocking networks. The directcurrent bias networks and direct current blocking networks of variousexamples permit the radio-frequency switching circuit to scaleaccordingly under increasingly large radio-frequency signal power, andensure the proper operation of each field effect transistor within thecircuit regardless of radio-frequency signal power handling requirementsof the radio-frequency circuit.

As discussed above, high power switching applications for radiofrequency signals are typically addressed using one or more PIN diodes.While PIN diodes offer improved switching speed when compared toconventional radio-frequency relays, they can require a significantdirect current bias current or voltage to maintain, or switch, biasconditions. In modern communication terminals, such as base stations andwireless devices, available power is a significant design factor, and incertain instances, the required power to switch a PIN diode may not beavailable. Accordingly, PIN diodes are not suitable for all high powerradio-frequency switching applications.

Various aspects and examples discussed herein provide high powerswitching functionality without the significant power (e.g., directcurrent bias current or voltage) requirements necessary to control PINdiodes during high power/voltage radio-frequency signal conditions. Thiscapability may be highly desirable in numerous applications. Forexample, in many communication terminals it is desirable that componentdevices exhibit stable performance over a wide variety ofradio-frequency signal conditions. Aspects and examples of theradio-frequency circuits, devices, modules, and processes discussedherein can meet these objectives for a range of such conditions,providing stable performance regardless of the radio-frequency signalpower. Specifically, aspects and examples may be adapted to scaleaccording to radio-frequency signal power handling requirements, and mayenable low power control (e.g., low direct current bias current orvoltage) during high power/voltage radio-frequency signals conditions.Accordingly, various aspects and examples disclosed herein may provideimportant functionality that is not available from conventionalradio-frequency devices.

It is to be appreciated that examples of the methods and apparatusesdiscussed herein are not limited in application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Themethods and apparatuses are capable of implementation in other examplesand of being practiced or of being carried out in various ways. Examplesof specific implementations are provided herein for illustrativepurposes only and are not intended to be limiting. Also, the phraseologyand terminology used herein is for the purpose of description and shouldnot be regarded as limiting. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.Any references to front and back, left and right, top and bottom, upperand lower, and vertical and horizontal are intended for convenience ofdescription, not to limit the present systems and methods or theircomponents to any one positional or spatial orientation.

FIG. 1A is a block diagram of one example of a radio-frequency circuit100 according to certain aspects and implementations. As illustrated,the radio-frequency circuit 100 may include a series of transistorsincluding at least a first transistor 106 and a second transistor 108,each having at least a source, a gate, and a drain, and a plurality ofdirect current bias networks including a first direct current biasnetwork 110 coupled to the gate of the first transistor 106, a seconddirect current bias network 112 coupled to the gate of the secondtransistor 108, and a third direct current bias network 114 coupled tothe drain of the first transistor 106 and the source of the secondtransistor 108. Each of the plurality of direct current bias networks110, 112, 114 may directly bias the corresponding transistor to direct aradio-frequency signal through the series of transistors 106, 108. Asfurther illustrated in FIG. 1A, the radio-frequency circuit 100 mayfurther include an input path 102 to receive the radio-frequency signaland an output path 104 to provide the radio-frequency signal.

FIG. 1B is more comprehensive block diagram of the radio-frequencycircuit 100 shown in FIG. 1A. That is, FIG. 1B illustrates one exampleof the radio-frequency circuit 100 which further includes a plurality ofvoltage distribution networks (e.g., a first voltage distributionnetwork 116 and a second voltage distribution network 118) and one ormore direct current blocking networks (e.g., a first direct currentblocking network 120 and a second direct current blocking network 122).Each direct current bias network 110, 112, 114 may be coupled to acorresponding bias source, such as the gate bias source 124 and thesource/drain bias source 126 illustrated in FIG. 1B. The first andsecond direct current bias networks 110, 112 are coupled to the gatebias source 124, and the third direct current bias network 114 iscoupled to the source/drain bias source 126. Specifically, in FIG. 1B,the first direct current bias network 110 is interposed between the gateof the first transistor 106 and the gate bias source 124, and the seconddirect current bias network 112 is interposed between the gate of thesecond transistor 108 and the gate bias source 124. In FIG. 1B, thethird direct current bias network 114 is interposed between a commonconnection between the drain of the first transistor 106 and the sourceof the second transistor 108, and the source/drain bias source 126.

While FIG. 1B illustrates the gate bias source 124 as a single biassource, in other examples the radio-frequency circuit 100 may include aseparate bias source for the gate of each transistor 106, 108. Forinstance, the radio-frequency circuit 100 may include a first gate biassource coupled to the first direct current bias network 110, and asecond gate bias source coupled to the second direct current biasnetwork 112. As further described below with reference to at least FIG.4, various components of the radio-frequency circuit 100 may beintegrated within a shared die and may be packaged within the sameradio-frequency module.

Though the components of several views of the drawings herein may beshown and described as discrete elements in a block diagram and may bereferred to as “circuit” or “circuitry,” unless otherwise indicated, theelements may be implemented as one of, or a combination of, analogcircuitry, digital circuitry, or one or more microprocessors executingsoftware instructions. Unless otherwise indicated, signal lines may beimplemented as discrete analog or digital signal lines. Unless otherwiseindicated, signals may be encoded in either digital or analog form;conventional digital-to-analog or analog-to-digital converters may notbe shown in the drawings.

According to various examples, the illustrated radio-frequency circuit100 may be configured to receive a radio-frequency signal at the inputpath 102 and route the radio-frequency signal through the series oftransistors 106, 108 to the output path 104. In various implementations,the radio-frequency circuit 100 may be configured to receive theradio-frequency signal in series or in shunt with the series oftransistors 106, 108. According to certain examples, the radio-frequencycircuit 100 may be used to provide one or more switching operations toselectively permit communication of the radio-frequency signal from theinput path 102 to the output path 104. For example, the input path 102may be coupled to an output transmission line of a radio-frequency poweramplifier. In various examples, the radio-frequency signal may be usedfor various purposes, such as selectively driving the antenna of acommunication terminal. Accordingly, the radio-frequency circuit 100 maybe included in numerous devices in which management of a radio-frequencysignal is important, such as a base-station or a wireless device (e.g.,a mobile phone).

In certain examples, each transistor (e.g., the first transistor 106 andthe second transistor 108) within the series of transistors includes athree-terminal transistor, such as a field effect transistor having agate, source, and drain. Specifically, each of the first transistor 106and second transistor 108 may include a field effect transistormanufactured from gallium arsenide (GaAs), gallium nitride (GaN), indiumgallium arsenide (InGaAs), or any other suitable material. While in oneexample, each transistor 106, 108 may be a metal-oxide-semiconductorfield-effect transistor, in various examples, the particular type offield effect transistor may depend on the application and the circuitdesign requirements. In particular examples, field effect transistorsoffer a benefit of a lower switching bias current or voltage whencompared to conventional PIN diodes.

In certain other examples, each transistor within the series oftransistors may include a field effect transistor having more than threeterminals. For instance, the first transistor 106 and the secondtransistor 108 may include a four-terminal or five-terminal field effecttransistor having a gate, source, drain, body, and/or substrate. Thatis, the type and configuration of each transistor 106, 108 within theseries of transistors may include any suitable transistor and may bechosen based on the desired application and performance of theradio-frequency circuit 100. The radio-frequency circuit 100 illustratedin FIG. 1B includes two transistors for the convenience of illustration,and in various other examples any suitable number of transistors may beincluded within the radio-frequency circuit 100. Specifically, theradio-frequency circuit 100 may be scaled according to increasingradio-frequency signal power conditions by the addition of one or moretransistors (and corresponding direct current bias networks and/orvoltage distribution networks). For example, the number of transistorswithin the given circuit 100 may be a function of the highestradio-frequency signal power that the radio-frequency circuit 100 isrequired to receive, the frequency of operation of the receivedradio-frequency signal, and the processes used to manufacture thetransistors. In particular, the number of transistors coupled in seriesmay be proportional to the breakdown voltage of the manufacturingprocess, and the maximum radio-frequency signal voltage.

In the illustrated example of FIGS. 1A-1B, each direct current biasnetwork 110, 112, 114 is coupled to at least one of the transistors 106,108 and configured to apply a current or voltage (e.g., direct currentbias current or voltage) to bias the corresponding transistor 106, 108.According to various examples, each direct current bias network 110,112, 114 may be driven by the coupled bias source. Application of thebias current or voltage from the direct current bias source may switchthe corresponding transistor 106, 108 between one or more desired statesof operation (i.e., saturation mode or cutoff mode). That is, eachtransistor 106, 108 may be dynamically controlled between an “ON” stateand an “OFF” state, or between the “OFF” state and the “ON” state.Control of each transistor 106, 108 between the “ON” state and the “OFF”state, or vice versa, will control the propagation of theradio-frequency signal from the input path 102 to the output path 104,as will be understood to one skilled in the art.

As discussed with reference to FIG. 1A, in FIG. 1B the first directcurrent bias network 110 is coupled to the gate of the first transistor106, and the second direct current bias network 112 is coupled to thegate of the second transistor 108. Each of the first direct current biasnetwork 110 and the second direct current bias network 112 is alsocoupled to the gate bias source 124. The gate bias source 124 mayinclude a power source configured to provide a gate bias signal (e.g.,direct current bias current or voltage) to the first direct current biasnetwork 110 and the second direct current bias network 112. Based on thereceived gate bias signal, the first direct current bias network 110 maydeliver a first bias current or voltage to the gate of the firsttransistor 106. Similarly, based on the received gate bias signal, thesecond direct current bias network 112 may deliver a second bias currentor voltage to the gate of the second transistor 108.

In certain examples, the third direct current bias network 114 iscoupled to at least one of the source and the drain of the firsttransistor 106, and at least one of the source and the drain of thesecond transistor 108. In the illustrated example, the third directcurrent bias network 114 is coupled to a common connection between thedrain of the first transistor 106 and the source of the secondtransistor 108. The radio-frequency circuit 100 also includes a firstvoltage distribution network 116 interposed between the third directcurrent bias network 114 and the first transistor 106, and a secondvoltage distribution network 118 interposed between the third directcurrent bias network 114 and the second transistor 108.

In the illustrated example, the third direct current bias network 114 iscoupled via the first voltage distribution network 116 to the source ofthe first transistor 106, and coupled via the second voltagedistribution network 118 to the drain of the second transistor 108. Thesource/drain bias source 126 may include a power source configured toprovide a source/drain bias signal (e.g., direct current bias current orvoltage) to the third direct current bias network 114. Based on thereceived source/drain bias signal, the third direct current bias network114 may apply a corresponding third bias current or voltage to thesource and/or drain of the first transistor 106 and the source and/ordrain of the second transistor 108.

According to certain examples, each of the first direct current biasnetwork 110, the second direct current bias network 112, and the thirddirect current bias network 114 may include a ¼ wave transformer, or aninductor circuit. In various examples, the ¼ wave transformer transformsthe impedance of the output end of the ¼ wave transformer (e.g., thetransistor end of the ¼ wave transformer) such that the output endappears as a compliment of the input end (e.g., the bias source end).For example, the each ¼ wave transformer may be implemented with aquarter wavelength of transmission line fabricated on a respectivesubstrate. As discussed herein, the quarter wavelength refers to thewavelength of the radio-frequency signal which is received at the inputpath 102 and propagates along the length of the respective ¼ wavetransformer. In certain other examples, each ¼ wave transformer mayinclude a pi-network including a first shunt capacitor, a seriesinductor, and a second shunt capacitor coupled to form a low-lossnetwork with an electrical length of approximately 90 degrees at thedesigned radio-frequency signal frequency. Each ¼ wave transformer,however implemented, is coupled in series (e.g., cascaded) with therespective bias source 124, 126 and load (e.g., the source, drain, orgate of the respective transistors 106, 108).

Each of the first voltage distribution network 116 and the secondvoltage distribution network 118 may include a plurality of circuitcomponents arranged to distribute the bias current or voltage receivedfrom the third direct current bias network 114 to one or both of thesource and drain of the corresponding transistors 106, 108. Forinstance, each voltage distribution network 116, 118 may include aplurality of resistors, or a plurality of resistors coupled in parallelwith one or more capacitors. As illustrated in FIG. 1B, the firstvoltage distribution network 116 may be coupled in parallel with thefirst transistor 106 and the second voltage distribution network 118 maybe coupled in parallel with the second transistor 108. The particularvalue of the resistors or capacitors of the voltage distributionnetworks 116, 118 may depend on the particular performance parameters ofthe associated transistors 106, 108 and the particular specifications ofthe associated radio-frequency circuit 100. Moreover, the values of eachcomponent of the voltage distribution networks 116, 118 may vary basedon fabrication processes.

In certain examples, each voltage distribution network 116, 118 isconfigured to equally divide the received voltage across each transistor106, 108 in the radio-frequency circuit 100, and in particular, wheneach of the transistors 106, 108 is biased in the OFF state. While insome examples, each voltage distribution network 116, 118 may be formedon a shared die with the transistors 106, 108, in certain other exampleseach of the voltage distribution networks 116, 118 may be formed on aseparate die and implemented on a shared substrate. Such an arrangementmay depend on the available manufacturing processes and/or the values ofthe resistors and capacitors.

Accordingly, each direct current bias network 110, 112, 114 may beoperated with each voltage distribution network 116, 118 to maintain thefirst transistor 106 and the second transistor 108 within a desiredstate of operation (i.e., saturation mode or cutoff mode) to provideswitching operations for the received radio-frequency signal.

As further illustrated in the example of FIG. 1B, one or more directcurrent blocking networks 120, 122 may be coupled to the output path 104and/or the input path 102 of the radio-frequency circuit 100. Forexample, the radio-frequency circuit 100 may include a first directcurrent blocking network 120 coupled to the input path 120 and a seconddirect current blocking network 122 coupled to the output path 104. Eachdirect current blocking network 120, 122 provides a low impedance to theradio-frequency signal and a high impedance to the direct current biascurrents and/or voltages. In at least one example, each direct currentblocking network 120, 122 may include a capacitor having a chosencapacitance value based on the particular application of theradio-frequency circuit 100 and/or the radio-frequency signal power.

FIG. 1C illustrates one example of a simplified block diagram of theradio-frequency circuit 100 illustrated in FIG. 1B. In particular, FIG.1C shows the first transistor 106, the first direct current bias network110, and the first voltage distribution network 116 arranged as a firstswitching circuit 128. FIG. 1C further shows the second transistor 108,the second direct current bias network 112, and the second voltagedistribution network 118 arranged as a second switching circuit 130.FIG. 1C further shows the gate bias source 124, the source/drain biassource 126, the plurality of switching circuits 128, 130 each coupled inparallel between the gate bias source 124 and the source/drain biassource 126, and each including the corresponding transistor (e.g.,transistors 106, 108) coupled in series with the correspondingtransistor of each of the other switching circuits. The direct currentbias network 114 is interposed between the source/drain bias source 126and each switching circuit 128, 130 of the plurality of switchingcircuits.

In FIG. 1C, and as also shown in FIG. 1B, the first switching circuit128 may include the first direct current bias network 110 and the firstvoltage distribution network 116 (in addition to the first transistor106), and the second switching circuit 130 may include the second directcurrent bias network 112 and the second voltage distribution network 118(in addition to the second transistor 108). While illustrated in FIG. 1Cas an arrangement of two switching circuits (i.e., the first switchingcircuit 128 and the second switching circuit 130), in various otherexamples the radio-frequency circuit 100 may include any number oftransistors, and, accordingly, any number of switching circuits. In suchan arrangement, each individual switching circuit may include one ormore transistors, a corresponding direct current bias network, and acorresponding voltage distribution network. Moreover, each switchingcircuit may be coupled to a shared direct current bias network, such asthe direct current bias network 114 illustrated in FIG. 1C.

Referring to FIG. 2, illustrated is one example of a radio-frequencyswitching device 200 according to certain aspects. In particular, theexample radio-frequency switching device 200 may incorporate one or moreof the radio-frequency circuit 100 shown in FIG. 1A. In the illustratedexample, the radio-frequency switching device 200 includes a signalinput path 202 configured to receive a radio-frequency signal, aplurality of signal output paths 204, 206, 208, 210 (e.g., IN/OUT ports)each to provide the radio-frequency signal, and a plurality ofradio-frequency sub-networks (e.g., first sub-network 212, secondsub-network 214, third sub-network 216, and fourth sub-network 218).Each radio-frequency sub-network 212, 214, 216, 218 may be interposedbetween the signal input path 202 and a signal output path 204, 206,208, 210 and positioned to route the radio-frequency signal between thesignal input path 202 and that signal output path 204, 206, 208, 210. InFIG. 2, the first sub-network 212 is coupled to the signal output path204, the second sub-network 214 is coupled to the signal output path206, the third sub-network 216 is coupled to the signal output path 208,and the fourth sub-network 218 is coupled to the signal output path 210.

While in FIG. 2, each IN/OUT port is described as an output path (e.g.,signal output paths 204, 206, 208, 210) for the convenience ofdescription, in various other implementations each IN/OUT port may beused as an input path, and the signal input path 202 may be used as theoutput path. Moreover, while FIG. 2 illustrates one example of a singlepole four-throw radio-frequency switching device for the sake ofillustration, various aspects and examples discussed herein are not solimited. That is, the radio-frequency switching device 200 may includeany number of sub-networks, and accordingly, any pole-count and/or anythrow count. For instance, the radio-frequency switching device 200 mayinclude two sub-networks for a single pole double-throw arrangement, twosub-networks for a double-throw double pole arrangement, or threesub-networks for a single pole triple throw arrangement, to name a fewexamples.

Each of the radio-frequency sub-networks 212, 214, 216, 218 within theexample radio-frequency switching device 200 illustrated in FIG. 2 mayinclude one or more radio-frequency circuits (shown generally ascircuits 220, 222, 224, 226, 236, 238, 240, 242), each radio-frequencycircuit having a series of transistors, similar to the radio-frequencycircuit 100 illustrated in FIG. 1A. Interposed between theradio-frequency circuits of each radio-frequency sub-networks 212, 214,216, 218 is a direct current blocking network (e.g., direct currentblocking networks 244, 246, 248, 250). Each radio-frequency circuitwithin a sub-network may be coupled in series and may be implemented ona shared die, as further discussed below with reference to FIG. 4.

FIG. 3 shows one example of an enhanced view of the radio-frequencysub-network 212 of the radio-frequency switching device 200 shown inFIG. 2. In particular, FIG. 3 shows the first radio-frequency circuit220 of the sub-network 212 coupled in series with the secondradio-frequency circuit 236 of the sub-network 212. A first directcurrent blocking network 244 is interposed between the firstradio-frequency circuit 220 and the second radio-frequency circuit 236,a second direct current blocking network 306 is coupled to the inputpath 308 of the first radio-frequency circuit 220, and a third directcurrent blocking network 312 is coupled to the output path 314 of thesecond radio-frequency circuit 236. FIG. 3 shows two radio-frequencycircuits 220, 236 for the convenience of illustration, and in variousother examples, each radio-frequency sub-network 212, 214, 216, 218shown in FIG. 2 may include any suitable number of radio-frequencycircuits. Additional radio-frequency circuits may be coupled to thesecond radio-frequency circuit 236 in a manner similar to which thesecond radio-frequency circuit 236 is coupled to the firstradio-frequency circuit 220.

Similar to the radio-frequency circuit 100 illustrated in FIG. 1A, eachradio-frequency circuit 220, 236 may include a series of one or moretransistors (e.g., first transistors 316, 320 and second transistors318, 322), a plurality of direct current bias networks (e.g., firstdirect current bias networks 324, 330, second direct current biasnetworks 326, 332, and third direct current bias networks 328, 334), anda plurality of voltage distribution networks (e.g., first voltagedistribution networks 336, 340 and second voltage distribution networks338, 342). Each direct current bias network 324, 326, 328, 330, 332, 334may be coupled to a corresponding bias voltage source such as the gatebias sources 344, 348 and the source/drain bias sources 346, 350.

Returning to FIG. 2, the input path of at least one of theradio-frequency circuits of a corresponding radio-frequency sub-network212, 214, 216, 218 may be coupled to the signal input path 202 of theradio-frequency switching device 200. Similarly, the output path of atleast one of the radio-frequency circuits of the correspondingradio-frequency sub-network 212, 214, 216, 218 may be coupled to atleast one of the output signal paths 204, 206, 208, 210 of theradio-frequency switching device 200. As such, control of eachindividual radio-frequency sub-network 212, 214, 216, 218, and theradio-frequency circuits therein, may selectively route aradio-frequency signal received at the signal input path 202 to adesired signal output path 204, 206, 208, 210.

In various examples, the radio-frequency switching device 200 includes aplurality of transmission lines, each transmission line interposedbetween the signal input path 202 and one of the radio-frequencysub-networks 212, 214, 216, 218. Specifically, each transmission linemay couple the signal input path 202 to an input path of aradio-frequency circuit within a given radio-frequency sub-network 212,214, 216, 218. Referring to the example of FIG. 2, the illustratedradio-frequency switching device 200 includes a first transmission line228 coupled to the first radio-frequency sub-network 212, a secondtransmission line 230 coupled to the second radio-frequency sub-network214, a third transmission line 232 coupled to the third radio-frequencysub-network 216, and a fourth transmission line 234 coupled to thefourth radio-frequency sub-network 218.

In certain examples, each transmission line 228, 230, 232, 234 includesa ¼ wave transformer, similar to the ¼ wave transformer included withinthe direct current bias networks 110, 112, 114 discussed with referenceto FIG. 1. As discussed above, each ¼ wave transformer transforms theimpedance on the output end of the corresponding transmission line(e.g., the radio-frequency sub-network end) to appear as the complimenton the input end (e.g., the signal input path end). Accordingly, wheneach transistor within the radio-frequency circuits of a radio-frequencysub-network is in an “ON” state, the signal input path 202 will see ahigh impedance (e.g., open circuit), and power will not flow to thecorresponding radio-frequency sub-network 212, 214, 216, 218. Incontrast, when each transistor within the radio-frequency circuits ofthe radio-frequency sub-network is in an “OFF” state (e.g., shortcircuit), the signal input path 202 will see the load impedance of thecorresponding radio-frequency sub-network.

For example, referring to the radio-frequency sub-networks 214, 218, ifthe transistors within the radio-frequency circuits 222, 238, 220, 236,224, 240 are biased in the “ON” state, and the transistors within theradio-frequency circuits 226, 242 are biased in the “OFF” state, theimpedance at the signal input path 202 (e.g., COMMON port) would be theimpedance value of the system (e.g., 50 ohms for a 50 ohm system) at thedesigned radio-frequency signal frequency. Similarly, the impedance atthe output 210 (e.g., IN/OUT(i+1) port) would be the impedance value ofthe system at the designed radio-frequency signal frequency. Since theimpedance looking into the input of each ¼ wave transformer is thecompliment of the impedance on the opposite side, if the transistors inradio-frequency circuits 222, 238 are biased in the “ON” state, theimpedance looking into the transmission line 230 from the signal inputpath 202 would be high (e.g., infinite in an ideal case). Accordingly,the received radio-frequency signal avoids this path, and is diverted tothe signal output path 210 of the radio-frequency sub-network 218.Likewise, if a signal is applied to the signal output path 210, it willbe directed to the signal input path 202. Similar operations may beperformed by the radio-frequency sub-networks 212, 214, 216.

Accordingly, various aspects and examples discussed herein provide highpower switching functionality without the significant power (e.g.,direct current bias current or voltage) requirements of conventionalhigh radio-frequency signal power switching devices. As discussed above,aspects and examples of the circuits, devices, and processes discussedherein can meet low power objectives for a range of such conditions,providing stable performance regardless of the radio-frequency signalpower. Specifically, aspects and examples may be adapted to scaleaccording to radio-frequency signal power handling requirements and toaccommodate high power/voltage radio-frequency signals conditions withminimal direct current bias current or voltages. Accordingly, variousaspects and examples disclosed herein may provide importantfunctionality that is not available from conventional radio-frequencydevices.

A radio-frequency circuit in accord with the aspects and examplesdescribed herein may be implemented in a number of topologies andphysical technologies. Any of the components thereof may be implementedin a substrate or in a die and may be designed for and manufactured fromvarious semiconductor materials, such as Silicon (Si), Germanium (Ge),Gallium arsenide (GaAs), for example, using various design technologies,such as complementary metal-oxide semiconductor (CMOS), Silicon oninsulator (SOI), double-diffused metal-oxide semiconductor (DMOS),laterally diffused metal-oxide semiconductor (LDMOS), bipolar CMOS/DMOS(BCD), pseudomorphic high-electron-mobility transistor (pHEMT),enhancement/depletion mode (E/D-mode) pHEMT, or various combinations ofthese or other materials and technologies. In certain examples, thedie(s) may be mounted upon or coupled to a substrate and packaged withina module.

FIG. 4 is a block diagram of one example of a module 400 that caninclude an implementation of the radio-frequency circuit 100 illustratedin FIG. 1A. The illustrated module 400 of FIG. 4 is discussed withincontinuing reference to the radio-frequency circuit illustrated in FIG.1A.

In the illustrated example of FIG. 4, the module 400 includes apackaging substrate 402 that is configured to receive a plurality ofcomponents. In some examples, such components can include a die 404having components of the radio-frequency circuit 100 described herein,such as the series of transistors 106, 108, the plurality of directcurrent bias networks 110, 112, 114, the plurality of voltagedistribution networks 116, 118, and/or the one or more direct currentblocking networks 120, 122. In some examples, other circuitry orcomponents 408 can be mounted on or formed on the packaging substrate402. In some examples, the packaging substrate 402 can include alaminate substrate.

In some examples, the module 400 can also include one or more packagingstructures to, for example, provide protection and facilitate easierhandling of the module 400. Such a packaging structure can include anovermold formed over the packaging substrate 402 and dimensioned tosubstantially encapsulate the various dies and components thereon. Asdiscussed above, it will be understood that although the module 400 isdescribed in the context of wirebond-based electrical connections, oneor more features of the present disclosure can also be implemented inother packaging configurations, including flip-chip configurations.

FIG. 5 is a block diagram of one example of a communication terminal 500in which the example module 400 of FIG. 4 can be used. While in oneexample the communication terminal 500 may be a base-station side of awireless network where radio-frequency signal power is naturally high(e.g., 100 Watts), in certain other examples the communication terminal500 may be a wireless communication device. The example wireless devicecan be a mobile device, such as a smart phone or tablet, for example. Byway of example, the communication terminal 500 can communicate inaccordance with Long Term Evolution (LTE). In this example, thecommunication terminal 500 can be configured to operate at one or morefrequency bands defined by an LTE standard. The communication terminal500 can alternatively or additionally be configured to communicate inaccordance with one or more other communication standards, including butnot limited to one or more of a Wi-Fi standard, a Bluetooth standard, a3G standard, a 4G standard or an Advanced LTE standard.

As illustrated in FIG. 5, the communication terminal 500 can include atransceiver 502, an antenna 504, power amplifiers 506, a controlcomponent 508, a computer readable storage medium 510, and at least oneprocessor 512. The module 400 can be electrically coupled to one or morecomponents of the of the power amplifiers 506. As will be appreciated bythose skilled in the art, the communication terminal 500 can includeelements that are not illustrated in FIG. 5 and/or a sub-combination ofthe illustrated elements.

The transceiver 502 can generate radio-frequency signals fortransmission via the antenna 504. Furthermore, the transceiver 502 canreceive incoming radio-frequency signals from the antenna 504. It willbe understood that various functionalities associated with transmittingand receiving of radio-frequency signals can be achieved by one or morecomponents that are collectively represented in FIG. 5 as thetransceiver 502. For example, a single component can be configured toprovide both transmitting and receiving functionalities. In anotherexample, transmitting and receiving functionalities can be provided byseparate components.

In FIG. 5, one or more output signals from the transceiver 502 aredepicted as being provided to the antenna 504 via one or moretransmission paths 514 through the module 400. In the exampleillustrated, different transmission paths 514 can represent output pathsassociated with different frequency bands (e.g., a high band and a lowband) and/or different power outputs. Similarly, one or more signalsfrom the antenna 504 are depicted as being provided to the transceiver502 via one or more receive paths 516 through the module 400. In theexample illustrated, different receive paths 516 can represent pathsassociated with different signaling modes and/or different receivefrequency bands. The communication terminal 500 can be adapted toinclude any suitable number of transmission paths 514 or receive paths516. The transmission paths 514 can include one or more power amplifiers506 to aid in boosting a radio-frequency signal having a relatively lowpower to a higher power suitable for transmission.

In certain examples, the antenna 504 can be connected to an antennaterminal on the module 400. Similarly, the transceiver 502 can beconnected to a radio-frequency terminal on the module 400 via one ormore of the transmission paths 514 or receive paths 516. As discussedabove, according to certain examples, the module 400 can direct areceived radio-frequency signal and facilitate switching between receiveand/or transmit paths, by selectively electrically connecting theantenna 504 to a selected transmit or receive path. Thus, one or more ofthe transmission paths 514 can be active while one or more of the othertransmission paths 514 are non-active, and similarly for the receivepaths 516. The module 400 can provide a number of switchingfunctionalities associated with an operation of the communicationterminal 500.

In certain examples, at least one processor 512 can be configured tofacilitate implementation of various processes on the communicationterminal 500. At least one processor 512 can be, for example, a specialpurpose processor. In certain implementations, the communicationterminal 500 can include a non-transitory computer readable medium 510,such as a memory, which can store computer program instructions that maybe provided to and executed by the at least one processor 512.

Some of the implementations described above have provided examples inconnection with mobile devices. However, the principles and advantagesof the examples can be used for any other systems or apparatus, such asany uplink cellular device, that could benefit from any of the circuitsdescribed herein. Any of the principles and advantages discussed hereincan be implemented in an electronic system that uses transistor basedswitches. Thus, aspects of this disclosure can be implemented in variouselectronic devices. Examples of the electronic devices can include, butare not limited to, consumer electronic products, parts of the consumerelectronic products, electronic test equipment, cellular communicationsinfrastructure such as a base station, a mobile phone such as a smartphone, a telephone, a television, a computer monitor, a computer, amodem, a hand held computer, a laptop computer, a tablet computer, anelectronic book reader, a wearable computer such as a smart watch, apersonal digital assistant (PDA), a microwave, a refrigerator, anautomobile, a stereo system, a DVD player, a CD player, a digital musicplayer such as an MP3 player, a radio, a camcorder, a camera, a digitalcamera, a portable memory chip, a health care monitoring device, avehicular electronics system such as an automotive electronics system oran avionics electronic system, a peripheral device, a clock, etc.Further, the electronic devices can include unfinished products.

As described above with reference to at least FIGS. 1A-1C, 2, and 3,several examples perform processes that provide a radio-frequencysignal. In some examples, these processes are executed by components ofradio-frequency circuit, such as the radio-frequency circuit 100described above with reference to FIGS. 1A-1C. One example of such aprocess is illustrated in FIG. 6. FIG. 6 is described with continuingreference to at least the radio-frequency circuit 100 shown in FIGS.1A-1C.

In the illustrated example of FIG. 6, the process 600 may include theacts of receiving a radio-frequency signal, receiving a first directcurrent bias from a first direct current bias network, receiving asecond direct current bias from a second direct current bias network,receiving a third direct current bias from a third direct current biasnetwork, directing the radio-frequency signal, and providing theradio-frequency signal at an output path. While not explicitlyillustrated in the example process flow of FIG. 6, in various examplesthe process 600 may include additional acts and processes. Such acts andprocess are discussed above in further detail with regards to theradio-frequency circuit 100 shown in FIGS. 1A-1C, and the exampleradio-frequency switching device 200 shown in FIG. 2.

In act 602, the process 600 may include receiving a radio-frequencysignal, such as an amplified radio-frequency signal, at an input path.For example, the process 600 may include receiving the radio-frequencysignal from an output transmission line of a radio-frequency poweramplifier in series or in shunt with the series of transistors 106, 108of the radio-frequency circuit 100. As discussed above with reference toat least FIG. 1A, the radio-frequency signal may be used for numerouspurposes, such as driving the antenna of a communication terminal. Oncereceived at the input path, the process 600 may include one or more actsof controlling a state of each transistor 106, 108 to manage thepropagation of the radio-frequency signal to the output path.

In act 604, the process 600 may include receiving a first direct currentbias from a first direct current bias network 110 at a first transistor106. In particular, act 604 may include applying a bias current orvoltage (e.g., a first direct current bias current or voltage) to thecorresponding first transistor 106 to directly bias the first transistor106. As discussed above, each transistor 106, 108 may include a fieldeffect transistor having a gate, a source, and a drain. In certainexamples, the first direct current bias network 110 may be coupled tothe gate of the first transistor 106, and the process 600 may includereceiving the first bias current or voltage from the first directcurrent bias network 110 at the gate of the first transistor 106.

In act 606, the process 600 may include receiving a second directcurrent bias from a second direct current bias network 112 at a secondtransistor 108. In particular, act 606 may include applying a biascurrent or voltage (e.g., a second direct current bias current orvoltage) to the corresponding second transistor 108 to directly bias thesecond transistor 108. In certain examples, the second direct currentbias network 112 may be coupled to the gate of the second transistor108, and the process 600 may include receiving the second bias currentor voltage from the second direct current bias network 112 at the gateof the second transistor 108.

In act 608, the process 600 may include receiving a third direct currentbias from a third direct current bias network 114 at the drain of thefirst transistor 106 and the source of the second transistor 108.Accordingly, the process 600 may include applying a bias current orvoltage (e.g., a third direct current bias current or voltage) to thedrain of the first transistor 106 to directly bias the first transistor106, and applying a bias current or voltage (e.g., the third directcurrent bias current or voltage) to the source of the second transistor108 to directly bias the second transistor 108.

In act 610, the process 600 may include directing the radio-frequencysignal from the input path through the first transistor 106 and thesecond transistor 108. In act 610, the process 600 may includecontrolling each direct current bias network to maintain (or switch)each transistor 106, 108 within the series of transistors to a desiredstate of operation (i.e., saturation mode or cutoff mode). Specifically,each direct current bias network 110, 112, 114 may be driven by acoupled bias source to switch the corresponding transistor 106, 108between an “ON” state and an “OFF” state, or between the “OFF” state andthe “ON” state. Control of each transistor 106, 108 between the “ON”state and the “OFF” state, or vice versa, controls the propagation ofthe radio-frequency signal from the input path to the output path, andselectively directs the radio-frequency signal. In act 612, the process600 may include providing the radio-frequency signal at an output path.

Accordingly, various aspects and examples discussed herein replace PINdiodes with field effect transistors to enable high powerradio-frequency switching based on a comparatively low direct currentbias current or voltage. Particular aspects and implementations mayinclude one or more direct current bias networks, and one or more directcurrent blocking networks, to directly bias each field effect transistorwithin the switching circuit to allow the circuit to scale accordinglyunder increasingly large radio-frequency signal power. Moreover, the oneor more direct current bias networks individually bias each field effecttransistor to ensure proper operation of each field effect transistorwithin the circuit regardless of the radio-frequency signal powerhandling requirements.

Having described above several aspects of at least one example, it is tobe appreciated various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be part of thisdisclosure and are intended to be within the scope of the disclosure.Accordingly, the foregoing description and drawings are by way ofexample only, and the scope of the disclosure should be determined fromproper construction of the appended claims, and their equivalents.

What is claimed is:
 1. A radio-frequency switching device comprising: aninput path configured to receive a radio-frequency signal; a pluralityof radio-frequency sub-networks each coupled to the input path andincluding at least a first radio-frequency circuit having a first seriesof directly biased transistors, a second radio-frequency circuit havinga second series of directly biased transistors, and a direct currentblocking network interposed between the first radio-frequency circuitand the second radio-frequency circuit; a plurality of output paths eachconfigured to provide the radio-frequency signal, each output path ofthe plurality of output paths corresponding to a respective one of theplurality of radio-frequency sub-networks; and a controller coupled tothe plurality of radio-frequency sub-networks and configured to controleach of the plurality of radio-frequency sub-networks to selectivelyroute the radio-frequency signal from the input path to at least oneoutput path of the plurality of output paths.
 2. The radio-frequencyswitching device of claim 1 further comprising a plurality oftransmission lines, at least one of the plurality of transmission linesbeing interposed between the input path and a corresponding one of theplurality of radio-frequency sub-networks.
 3. The radio-frequencyswitching device of claim 2 wherein each of the plurality oftransmission lines is a ¼ wavelength transformer.
 4. The radio-frequencyswitching device of claim 3 wherein the controller is configured tocontrol each of the plurality of radio-frequency sub-networks to operatein one of a first mode of operation to present a load impedance to theinput path and a second mode of operation to present a high impedance tothe input path.
 5. The radio-frequency switching device of claim 4wherein the controller is configured to selectively route theradio-frequency signal from the input path to the at least one outputpath by controlling the at least one radio-frequency sub-networkcorresponding to the at least one output path to operate in the firstmode of operation.
 6. The radio-frequency switching device of claim 5wherein the controller is further configured to control each respectiveradio-frequency sub-network of the plurality of radio-frequencysub-networks that is other than the at least one radio-frequencysub-network to operate in the second mode of operation.
 7. Theradio-frequency switching device of claim 4 wherein the first series oftransistors of each respective radio-frequency sub-network includes afirst transistor and a second transistor, and the second series oftransistors of each respective sub-network includes a third transistorand a fourth transistor.
 8. The radio-frequency switching device ofclaim 7 wherein the controller is configured to control each respectiveradio-frequency sub-network to operate in the first mode of operation bycontrolling each transistor of the first and second series oftransistors to operate in a non-conductive state.
 9. The radio-frequencyswitching device of claim 7 wherein the controller is configured tocontrol each respective radio-frequency sub-network to operate in thesecond mode of operation by controlling each transistor of the first andsecond series of transistors to operate in a conductive state.
 10. Aradio-frequency switching device comprising: a plurality ofradio-frequency sub-networks each including at least a firstradio-frequency circuit having a first series of directly biasedtransistors, a second radio-frequency circuit having a second series ofdirectly biased transistors, and a direct current blocking networkinterposed between the first radio-frequency circuit and the secondradio-frequency circuit; a plurality of input paths each configured toreceive a radio-frequency signal, each input path of the plurality ofinput paths corresponding to a respective one of the plurality ofradio-frequency sub-networks; an output path coupled to the plurality ofradio-frequency sub-networks and configured to provide theradio-frequency signal; and a controller coupled to the plurality ofradio-frequency sub-networks and configured to control each of theplurality of radio-frequency sub-networks to selectively route theradio-frequency signal from at least one input path of the plurality ofinput paths to the output path.
 11. The radio-frequency switching deviceof claim 10 further comprising a plurality of transmission lines, atleast one of the plurality of transmission lines being interposedbetween the output path and a corresponding one of the plurality ofradio-frequency sub-networks.
 12. The radio-frequency switching deviceof claim 11 wherein each of the plurality of transmission lines is a ¼wavelength transformer.
 13. The radio-frequency switching device ofclaim 11 wherein the first series of transistors of each respectiveradio-frequency sub-network includes a first transistor and a secondtransistor, and the second series of transistors of each respectivesub-network includes a third transistor and a fourth transistor.
 14. Theradio-frequency switching device of claim 13 wherein the controller isconfigured to operate each respective radio-frequency sub-network in afirst mode of operation by controlling each transistor of the first andsecond series of transistors to operate in a non-conductive state. 15.The radio-frequency switching device of claim 14 wherein the controlleris configured to operate each respective radio-frequency sub-network ina second mode of operation by controlling each transistor of the firstand second series of transistors to operate in a conductive state. 16.The radio-frequency switching device of claim 15 wherein the controlleris configured to selectively route the radio-frequency signal from theat least one input path to the output path by controlling the at leastone radio-frequency sub-network corresponding to the at least one inputpath to operate in the first mode of operation.
 17. The radio-frequencyswitching device of claim 16 wherein the controller is furtherconfigured to control each respective radio-frequency sub-network of theplurality of radio-frequency sub-networks that is other than the atleast one radio-frequency sub-network to operate in the second mode ofoperation.
 18. A method for operating a radio-frequency switching deviceto provide a radio-frequency signal, the radio-frequency switchingdevice including a plurality of radio-frequency sub-networks, the methodcomprising: receiving a radio-frequency signal at an input path;controlling at least one radio-frequency sub-network of the plurality ofradio-frequency sub-networks to operate in a first mode of operation topresent a load impedance to the input path; controlling each respectiveradio-frequency sub-network of the plurality of radio-frequencysub-networks that is other than the at least one radio-frequencysub-network to operate in a second mode of operation to present a highimpedance to the input path; directing the radio-frequency signal fromthe input path through the at least one radio-frequency sub-network; andproviding the radio-frequency signal at an output path corresponding tothe at least one radio-frequency sub-network.
 19. The method of claim 18wherein controlling each radio-frequency sub-network to operate in thefirst mode of operation further comprises controlling a series oftransistors within the at least one radio-frequency sub-network tooperate in a non-conductive state
 20. The method of claim 18 whereincontrolling each radio-frequency sub-network to operate in the secondmode of operation further comprises controlling a series of transistorswithin the radio-frequency sub-network to operate in a conductive state.